2 sentences

1. 气温陡然下降，让人感到一阵寒意。

   qì​wēn dǒu​rán xià​jiàng, ràng rén gǎn​dào yī zhèn hán​yì.

   The temperature dropped suddenly, sending a chill through the air.

   Source: Dong Chinese Dictionary

2. 刚才还是晴空万里，天气陡然变得阴冷起来。

   gāng​cái hái​shi qíng​kōng​wàn​lǐ, tiān​qì dǒu​rán biàn de yīn​lěng qi​lai.

   The sky was clear just a moment ago, but the weather suddenly turned cold and gloomy.

   Source: Dong Chinese Dictionary